Many cytokines are known as humoral factors involved in the growth and differentiation of various types of cells, or in the activation of differentiated mature cell functions. Cytokine-stimulated cells produce different types of cytokines, thereby forming networks of multiple cytokines in the body. Biological homeostasis is maintained by a delicate balance of the mutual regulation between cytokines in these networks. Many inflammatory diseases are thought to result from a failure of such cytokine networks. Thus, monoclonal antibody-based anti-cytokine therapy is drawing much attention. For example, anti-TNF antibodies and anti-IL-6 receptor antibodies have been demonstrated to be highly effective clinically. On the other hand, there are many examples of failure where no therapeutic effects were produced when a single cytokine, such as IL-4, was blocked alone, due to the activation of compensatory pathways in actual pathological conditions.
The present inventors succeeded in isolating a novel cytokine receptor NR10 that was highly homologous to gp130, a receptor for IL-6 signal transduction (Patent Document 1). NR10 forms a heterodimer with oncostatin M receptor (OSMR) and functions as an IL-31 receptor (Non-patent Document 1). Regarding IL-31, it has been reported that transgenic mice overexpressing IL-31 spontaneously develop pruritic dermatitis (Patent Document 2).
Antibodies that bind to NR10 and inhibit the binding between NR10 and IL-31 may be effective in treating inflammatory diseases. For clinical use, anti-NR10 antibodies are required to have low immunogenicity. Furthermore, in order to achieve high therapeutic effects, antibodies with strong NR10-binding or neutralizing activity are desired.
Prior art documents of the present invention are described below.    Patent Document 1: WO00/75314    Patent Document 2: WO03/060090    Non-patent Document 1: IL-31 is associated with cutaneous lymphocyte antigen-positive skin homing T cells in patients with atopic dermatitis, J Allergy Clin Immunol. 2006 February; 117(2): 418-25.